When having sex in a doggystyle fashion, the male will only have one chance for a Mountain Spew. Upon entry, the male must ram his cock into her Vascular Chasm Cavity as hard as possible, if upon impact the female screams and saliva exits the mouth, the male has successfully completed the Mountain Spew. Also see Mountain Spew: Code Red.

Jane: Fuck you Clark, that really hurt!!!
Clark:(on phone) DUDE!!! I DID IT!!! I DID THE MOUNTAIN SPEW!!! And it might have been a Code Red!!!
Jane: (crying) You asshole! I'm gonna tell everyone that you have Genital Warts!!
(Superman then ripped her in half)